1. Field of the Invention
The present invention relates to a machining program execution method for an NC device.
2. Description of the Related Art
There are various machining programs, which are executed by an NC device, including machining programs for rough machining, intermediate finish machining, finish machining, etc. In order to effectuate machining control of a machine tool by means of the NC device, parameters for the feed rate, acceleration/deceleration control, main spindle control, etc., required for the drive control of various parts of the machine tool, must be set previously in the NC device, besides the machining program.
Conventionally, the parameters are initially set beforehand in the NC device by the manufacturer, in consideration of the convenience and wishes of a user who utilizes the NC device or the machine tool. As long as the values of the parameters are kept fixed, however, it is hard to meet all of machining conditions, including rough machining, intermediate finish machining, finish machining, etc.
To cope with this problem, the NC device is provided with a function for modifying the setting of the parameters.
According to the conventional NC device, after bringing the NC device to a data input mode or an emergency stop state, desired parameter values are inputted by assigning parameter numbers by means of softkeys or ten-keys of a manual data input device attached to the NC device, or the parameter values are reloaded by setting a parameter tape in a tape reader to read the desired parameter values. All these operations are carried out manually, and the NC device is in an alarm state during these operations, so that the parameter reloading operation cannot be carried out in parallel with the execution of the machining programs.
In the case of lathing or milling operation, the machining processings, such as the rough machining, intermediate finish machining, finish machining, etc., can be executed in succession by repeatedly executing the same machining programs, while program-controlling the revolution speed, offset, etc. However, as discussed previously, in the case of a conventional NC device, the parameters can not be reloaded during the execution of the machining programs. Even during intervals between individual machining processings, such as rough machining, intermediate finish machining, finish machining, etc., the setting of parameter tape and operation of the manual data input device need to be done by the operator. Therefore, resetting the parameters in response to the change of the machining processing is practically impossible without interrupting automatic and continuous execution of machining processings.
Conventionally, in continuously performing the automatic operation for the individual machining processings, set values meeting the requirements of the machining accuracy of the finish machining are set as parameters in advance, and machining control is effected using parameters for the finish machining throughout the machining processings including the rough machining, intermediate finish machining, finish machining, etc. Naturally, however, the time required for the entire machining becomes longer than necessary, bringing poor machining efficiency. On the other hand, if a series of machining control operations are carried out with the parameters set for the rough machining in order to save the time required for machining, proper finish machining can not be achieved.
Modern NC devices and machine tools have advanced functions, which enable a series of machining processings to be executed continuously by means of a tool changing function of the machine tools, program editing function of the NC devices, etc. even when different tools or machining programs needed to be used depending on the machining processings, including the rough machining, intermediate finish machining, finish machining, etc. So far, however, the function for automatically re-setting the parameters has not been made available. Thus, there still remains a problem such that the required machining time increases or the finish machining is unsatisfactory when the machining operation is required to be carried out continuously. Even in the case where the machining processings are carried out individually, it is very troublesome for the operator to set the parameters manually every time the machining programs are changed.